var arr = [1,2];
var arr1 = arr;
arr1.push(3);
console.log(arr.valueOf());

var a = "2";
var b = "1";
console.log(a-b);
b = false;
console.log(a-b);



var car = new Object();
if(car){
    console.log("汽车");
    
}
console.log(""-2);

console.log([]-2);
console.log(Function+"2");

